Texas Instruments SN74LVC2G157DCU3

Overview

SN74LVC2G157 from Texas Instruments is a single 2-line to 1-line data selector multiplexer with true and complementary outputs (Y and Y), designed for 1.65-V to 5.5-V V_CC operation, supporting 5-V I/O tolerance and delivering 6 ns max propagation delay at 3.3 V - used in sensor signal routing on embedded PC and HVAC control boards.

For engineers reviewing the SN74LVC2G157 datasheet, SN74LVC2G157 pinout, SN74LVC2G157 application, or SN74LVC2G157 equivalent, key selection criteria include I_off-enabled partial-power-down capability, ±24-mA output drive at 3.3 V, 5.5-V input tolerance for level translation, and NanoFree™ VSSOP-8 package compatibility with high-density layouts.

Technical Context

This device implements a positive-logic 2:1 multiplexer with active-low common strobe (G) controlling data routing: when G = L, A/B selects between inputs A and B to drive Y (true) and Y (complement); when G = H, both outputs are forced to opposite logic states (Y = L, Y = H). Its standard CMOS inputs and balanced push-pull outputs support bidirectional voltage translation across 1.65–5.5 V domains.

The I_off circuitry disables outputs during power-down, blocking back-drive current and enabling live insertion; negative clamping diodes protect inputs/outputs against −0.5 V transients, while ESD ratings exceed 2000-V HBM and 1000-V CDM per JESD22.

Key Specifications

Pinout & Package

SN74LVC2G157DCU uses an 8-pin Very Thin Shrink Small-Outline Package (VSSOP) with 2.30 mm × 2.00 mm body size and 0.5-mm lead pitch - optimized for space-constrained PCBs in portable and embedded systems.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 2:1 multiplexer applications.

Compared with SN74LVC2G157DCU3, SN74LVC1G157DBVR trades complementary output capability for 40% smaller footprint, while 74LVC2G157GW,125 offers identical functionality in a thermally optimized package - neither is pin-compatible, requiring layout revision.

Availability

SN74LVC2G157 is available at Aetrix Electronics and suitable for barcode scanner signal routing, HVAC sensor consolidation, and wireless data access card interface requiring stable component supply across industrial temperature ranges (−40°C to +85°C).

Supply support for SN74LVC2G157 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with over 90 years of innovation in precision logic, power management, and signal chain solutions.

The SN74LVC2G157 belongs to TI's LVC (Low-Voltage CMOS) logic family - engineered for mixed-voltage interoperability, low dynamic power, and robust I/O tolerance in space- and power-sensitive embedded systems.

FAQ

What is the maximum capacitive load SN74LVC2G157 can drive while meeting datasheet timing specs?

The SN74LVC2G157 is characterized for loads up to 50 pF at V_CC = 3.3 V and 1.8 V. Driving >50 pF increases propagation delay nonlinearly - at 70 pF, t_pd exceeds 6 ns by ~35%. For reliable operation within spec, keep total load (trace + receiver input + probe) ≤50 pF. The SN74LVC2G157 datasheet specifies this limit in Section 9.2.1.1.

Does SN74LVC2G157 support level translation between 5-V and 1.8-V logic domains?

Yes - SN74LVC2G157 accepts 5.5-V inputs regardless of V_CC, enabling down-translation from 5-V sources to 1.8-V outputs. When V_CC = 1.8 V, VOH remains ≥1.2 V (I_OH = –4 mA), compatible with 1.8-V CMOS inputs. This behavior is confirmed in Section 6.3 (Recommended Operating Conditions) and Feature #9 of the datasheet.

How does the I_off feature protect SN74LVC2G157 during partial power-down?

When V_CC = 0 V, SN74LVC2G157's I_off circuitry disables all outputs, limiting leakage to ±10 µA even with 5.5-V signals applied to A, B, A/B, or G. This prevents back-current flow that could damage upstream drivers or disrupt other powered rails. The mechanism is detailed in Section 8.1 and Figure 3 of the SN74LVC2G157 datasheet.

Can SN74LVC2G157DCU3 be used in place of SN74LVC2G157DCT in existing designs?

No - SN74LVC2G157DCU3 (VSSOP-8) and SN74LVC2G157DCT (SSOP-8) share identical pinout and logic function but differ in package dimensions (2.30 mm × 2.00 mm vs. 2.95 mm × 2.80 mm) and thermal resistance (R_θJA = 289.9°C/W vs. 192.0°C/W). PCB redesign is required for footprint and solder paste stencil changes.

What is the purpose of the complementary Y output on SN74LVC2G157?

The Y output provides the logical inverse of Y, eliminating need for external inverters in differential signaling, enable/disable logic, or XOR-based encoding. In the SN74LVC2G157 function table (Section 8.4), Y and Y are guaranteed opposite states when G = L - verified across full V_CC and temperature range per Section 6.5.